Rewards systems for permitting a user to motivate one or more other users to perform predetermined activities are provided. A rewards system of the present invention can permit a supervisory user to set up rewards allocation parameters by which the rewards system can automatically distribute rewards to a subordinate user. Once the subordinate user has input data about his activities, the rewards system can determine the appropriate rewards to distribute to the subordinate user account based on the data and the rewards allocation parameters. A rewards system of the present invention also can permit a user to challenge one or more users to a competition. Based on data about the competitors' activities and user-defined allocation parameters, the rewards system can automatically distribute rewards to the user account(s) of victorious competitor(s).